BRONTOTHERIUM
The term "brontothere", meaning thunder - beast, was a
product of Sioux Indian mythology. The Brontotherium they
were referring to was a large Oligocene mammal, distantly related
to the rhinoceros, and had a forked "horn" on its snout.
Being larger in the males than in the females, this horn was
probably used in fighting, much like those of deer and antelope
today. The brontotherium died out as the great forests
were replaced by grasslands where horses, rhinos and other mammals
became more abundant.